MONTPELIER — The District 5 Environmental Commission has issued an Act 250 permit for the multimillion-dollar biomass heating plant that will serve the state complex, city municipal buildings and several businesses.

The joint city-state partnership involves two separate components: the construction of a new biomass plant on the site of the old boiler behind the Department of Motor Vehicles building at 120 State St., which is the state’s share of the project; and the city’s construction of the distribution system that will bring the wood-fired heat to the city’s project participants.

The city began work on its part of the project in April and is currently working on two sites in the city, while the state has been waiting for several permits before it could start construction on the plant itself. With Tuesday’s issuance of the Act 250 permit, the state must now acquire only a fire permit in order to begin construction.

“Everything that the state needed to address has been addressed,” said Terese Churchill, of EverGreen Environmental Health & Safety, who has been a consultant on the project. “All of the concerns have been taken care of.”

The state once hoped to have the plant operating by October but has acknowledged the start date will be later. Officials have said that backup measures are in place to provide heat until the plant comes online.

Among the issues addressed during the permit process, which looks at 10 criteria governing environmental impacts, were the plant’s placement in the city’s historic district, the possible use of the site for educational purposes, and the placement of a trailer for a temporary construction field office in the flood plain. The current boiler plant extends into the FEMA-designated floodway, while the new addition will not.

The state will use a combination of measures to address any flooding concerns. They include elevating the new parts of the structure above flood level, flood-proofing the existing structure, and anchoring the building.

The permit also states that the construction trailer intended for the site must either be moved out of the FEMA-designated floodway, or — if it remains — that it must be easily movable, or certified by a professional engineer to not magnify problems at the site caused by any flooding.

Because the building lies within the historic district, it must adhere to historic preservation guidelines, which the state outlined in its permit application. The original boiler plant will be documented photographically according to historic preservation guidelines before it’s demolished. The original chimney will be retained.

The permit also states that a “qualified archaeological monitor” must be on site during any excavations that are “below the existing fill adjacent to the state power plant between the railroad tracks and State Street or outside of existing streets or buried utility line corridors, to identify and record any cultural resources discovered during the excavations.”

The city, in consultation with the Vermont Division for Historic Preservation, will also produce a public education project supporting energy conservation in historic buildings.

What the permit does not include is any language regarding a public viewing platform that was originally conceived as part of an educational component of the project. After the District 5 commission questioned the safety of having groups of students traverse the often busy DMV parking lot to get to the viewing platform, the state removed all mention of an educational component at the site, although the platform will still be built.

The permit language concluded that the “biomass plant is consistent with the goals of both the Montpelier Master Plan (2008) and the Central Vermont Regional Plan in that it promotes an efficient use of energy and supplies the capitol complex and downtown core of Montpelier with a biomass heat supply.”

Reached by telephone while on vacation, the state’s district heat project manager, Joe Aja, said he was glad to have the permit in hand although he hadn’t yet had a chance to review it. For that reason he couldn’t comment on how soon the state would begin construction of the plant.